Hydraulic bicycle brake

ABSTRACT

A hydraulic bicycle brake is kept free of leakage thanks to the fact that a hollow body is utilized, consisting of an elastic encasement (7) connected on one side with the brake piston (17) and on the other side with the inlet flange (18), having a connection to a master cylinder by means of a fluid line; whereat due to this connection of piston (17), encasement (7) and inlet flange (18) there isn&#39;t any loss of fluid and the loads due to pressure and strain exerted onto the elastic part of the hollow body respectively in the transition zone: piston bottom--encasement and solid piston bottom, have less effects than observed for common pot-like shaped diaphragm seals, because of shear-, compression- and tensile forces as well as bending moments being by their distribution on the different materials respectively their connection of less influence, thanks to this make, comprising two different materials and thus foreseeing greater security, better durability and longer service life.

BACKGROUND OF THE INVENTION

The invention concerns a bicycle brake with at least one master cylinderconnected with a hand lever and at least one wheel cylinder or brakecylinder and, connecting the cylinders, a hydraulic fluid brake lineopening at both ends into a hollow body of variable volume whereas it ispossible to reduce the volume in the master cylinder by means of anorgan operated by the hand lever a against an accumulator.

Actuation of the master cylinder presses hydraulic fluid out of it andinto two brake cylinders in opposite position and so the pistons withbrake shoes attached on the piston rods are pushed in direction of thewheel rim edge. Contact between brake shoes and rim edge leads withinthe master cylinder or the brake cylinder to building up of hydrostaticpressure, transformed by means of the brake shoes to braking force andfriction.

By decreasing the force exerted by hand, or loosening the hand lever,the spring positioned in the master cylinder and acting as a forceaccumulator pushes the piston back to its starting position, thusleaving the system without any transferable or braking force.

To have minimum maintenance and optimal braking conditions the inventordecided for applying a closed and therefore leakproof hydraulic pressuresystem.

SUMMARY OF THE INVENTION

To make the piston exert the maximum force onto the wheel rim edge andto preserve a leakproof system, the inventor decided for a hollow bodyconsisting of an elastic, in its cylindrical part well deformablematerial as casing whereas a solid, not easily deformable material isforeseen for the front or bottom region. These two, totally differentmaterials will, depending on the application as master cylinder or brakecylinder, be adequately formed and connected making them hydraulicallyimpermeable.

In contrast to a common known pot-like diaphragm seal where forces andalso interior pressure act upon the cylindrical and bottom region of theelastic material as well, the solution following the invention, existingmaximum forces in axial direction here are exerted upon the hard solidmaterial i.e. there are hardly any transverse loads or bending moments,increasing thus service durability or service life compared to knownpot-like diaphragm seals.

Maximum tensions existing at the bottom of the piston, especially in thecenter thereof, are again unimportant compared to the potlike diaphragmseal for there isn't at this place any elastic or soft material to becrushed or torn by fluid pressure and a hard piston.

For a common known pot-like diaphragm seal moving axially without thepossibility to unwind, the loads as described can be compared to loadsexisting during deep-drawing of steel or aluminum.

Both frontal ring areas of the elastic casing of the master cylinder areconnected hydraulically tight with the bottom,of the guiding flange andwith the back of the master piston. By moving the piston directlyconnected with the piston rod, having an outer diameter equal to theinner diameter of the hollow body, in direction of the cylinder bottomwhich has an opening connected with a fluid line, a volume reduction inthe master cylinder will be created and so a rise of hydrostaticpressure. The elastic casing will, solidly fixed to the bottom of theguiding flange as well as to the back of the piston, be extended byaxial displacement and pressed against the outer diameter of the pistonrod by fluid pressure in the cylinder.

The hydraulic fluid, displaced in the master cylinder, flows into thebrake cylinder by use of the fluid line.

Both frontal ring areas of the elastic casing are tightly connected withthe bottom of the piston and the bottom of the brake cylinder where thislatter has an opening connected with the fluid line.

The entering fluid acting onto the bottom of the piston and piston rodwith brake shoe fixed on its fore-end presses the piston forward towardsthe wheel rim edge or another body of the braking stem as e.g. a brakedisc connected with the bicycle wheel.

By this increase of volume and after the contact between brake shoe andwheel rim edge increasing hydrostatic pressure the elastic casing isextended in axial direction and its diameter also increased, is pressedagainst the inner cylinder wall.

To assure an as long as possible service life of the elastic innerencasement an antifriction substance is applied onto the piston rod ofthe main cylinder as well as onto the inner wall Y the brake cylinderand by means of a wiping ring or other sealing element protectionagainst contamination from outside as by dirt, dust and humidity issecured and so the friction between elastic casing and piston rod, orelastic casing and cylinder wall will be as low as possible.

This ingeniously contrived form of the hollow body makes its use forwheel rim edge brakes as also for disc brakes possible. For the discbrake the inventor chose the floating caliper type.

The floating caliper disc brake makes use of a ball joint with adjoinedcylindrical sleeve having an outer diameter smaller than the diameter ofthe ball joint, giving so the appearance of a spherical gudgeon. Itfulfills, together with the brake cylinder, the task of a guiding pin. Abore is going through this special joint and the size of this bore is sothat it can take the round disc brake cylinder and an existing minimumgap or clearance allows the brake cylinder an oscillating movement. Aslot is longitudinally milled into the sleeve. A pin fixed in verticalposition in the brake cylinder fits into this slot, preventing the brakecylinder from turning around within the sleeve. Minimum length of thisslot is given by the width or diameter of the pin plus maximum amplitudeof the oscillating motion of the brake cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages, features and details of the invention appear fromthe following descriptions as well as from the drawings which thefollowing

FIG. 1: Detail of the brake cylinder in longitudinal section

FIG. 2: Detail of the Master cylinder in longitudinal section

FIG. 3: Top view of the arrangement of brake cylinder with tiltablesupports and cross section of a bicycle tire and wheel rim

FIG. 4: Side view of the tiltable support with partial section

FIG. 5: Side view of the U-shaped support and partially broken-outsection of the clamp

FIG. 6: Top view of the section of the disc brake with view of the wheelhub

FIG. 7: Sketch-like view of a bicycle with wheel rim brakes attached

FIG. 8: Sketch-like view of a bicycle with disc brakes attached

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A bicycle brake for a bicycle as shown by FIG. 7 and FIG. 8 consists, asshown in FIG. 2, of a master cylinder with hand lever (2) and one brakefluid line (16) going out from the master cylinder is directly connectedwith the brake cylinder (44) acting upon the brake disc (47), as shownin FIG. 6, or in connection with a Y-shaped distributor and two brakefluid lines (26), as shown in FIG. 1, coming out from it, as shown inFIG. 3, brake fluid supply is possible for two more brake cylinders.

The brake cylinders (24) are attached to the bicycle by means of aU-shaped support (40), as shown in FIG. 5 or by means of a tiltablesupport (27), as shown in FIGS. 3 and 4.

Whereas the U-shaped support (40) is fastened on the fork head thebridge by bolt (60) and nut, as shown in FIG. 5, the support (27) oughtto be fixed on the frame tube or fork tube (38), as shown in FIG. 4, bymeans of the intermediate bolt (29), this latter to be bonded to thefork tube, e.g. by soldering, and extending substantially parallel towheel rim 37, as shown in FIG. 3.

Referring now to FIG. 3, for the adjustment of the brake shoes to thewheel rim edge of a wheel rim (37) whereat the brake is functioning likean opposed cylinder engine, the brake cylinder (24) can,by means of theslotted spherical joint (21), as shown in FIG. 4, incorporated in thesupport (27) be moved in a swiveling and also oscillating motion and sothe precise position of the brake shoe and the correct distance betweenbrake shoe tip and wheel rim edge are attained. The brake shoe (19)adjusted, the brake cylinder can be fixed due to the gripping action ofthe slotted spherical joint (21) by tightening the bolts (32) of theslotted support (27).

For fast replacement of the wheel or the brake shoes (19) the support(27) can be tilted by an angle, and as shown in FIG. 3. To be tiltablethe support (27) has below the bore for locating the spherical joint(21), as shown in FIG. 4, a parallel in radial direction positionedhexagonal bore, having in the mid-region of its depth a circularturn-out (28) with a diameter to be larger than the hexagon-cornerdistance and a minimum depth which equals the length of that hexagon(30) positioned near the fox tube (38,39), the frontal side (52,33) ofthe laterally displaced support (27) overshooting the hexagon (31) infront position. It is to be kept in mind that the hexagons (30,31) havea beginning and an end only where the two frontal sides of the hexagonalopening of the support (27) are located. Or, the minimum length of theturn-out has to be equal to the length of the hexagon (31) positioned atthe front face (52) of the support (27) and the bolt head (34) of bolt(29). Of independent inventive importance is further the fact that inlieu of a hexagon another multiple-cornered bolt or a toothed bolt canbe used.

If now the support (2Y) is to be tilted, as shown in FIG. 4, it has tobe pushed beyond the rear hexagon (30) towards the fork tube (38,39),whereas a pin, to be taken off before or a pressure spring (33), pushingthe support (27) against the head of the bolt (34), are acting aslocking or safety devices.

By actuation of the hand lever (2) around a joint (14) the threaded pinor set screw (3) held in a rotatable shaft of the joint (13) is pushedagainst the pushing boat or the piston rod (5) whereby this latter asguided by flange (6) is moving the disc piston (8) forward against aspring (11) in the direction of the cylinder bottom whereby thehydraulic fluid flowing out of the cylinder (9) through a nipple orbrake line coupling (10) and the hydraulic line (16) and through aY-distributor, not described in detail here, which divides the volume ofthe fluid to de then conducted into the inner space (22) of the twobrake cylinders (24), as shown in FIGS. 1 and 3, attached on the leftand right side whereas the volume of the conducted fluid depends on theway or course of the brake shoes (19) and the distribution of thehydraulic fluid following the laws of such pressure systems.

The hydraulic fluid entering the interior (22) of the cylinder (24) withleakproof connection on one side within the brake piston (17) and on theother side with an inlet flange (18), as shown in FIG. 1, pushes thedisc piston (17) forward while the elastic casing (7) is extending andthe circular region thereof will be pressed against the wall of thebrake cylinder (24) until the brake shoe (19) has contact with the wheelrim edge. Pushing further by hand the hand lever (2) leads to a rise ofhydrostatic pressure upon the disc piston (17) and piston head (51) andthus upon the brake shoe. Pistons (17, 43) have an annular groove forholding therein a gasket ring (12), as shown in FIGS. 1 and 6,respectively.

The brake piston (17) for holding the brake shoe (19) is formed so thatin partial regions of a front surface of piston (17), an inward bentbase of the brake shoe (19) can snap into a circular groove of thepiston (17). The brake shoe exerts a hook-like grip onto the frontsurface of the piston wherein the front surface is in close contact withthe base of the brake shoe for the transfer of braking forces. Thepiston head (51) has a cylindrical shape whereat radial forces arereceived.

Referring to FIG. 6, it is evident that the leakproof hydraulic systemdescribed here, can also be applied for disc brakes. With reference toFIG. 2, the hydraulic fluid will be pressed out of the space (9) of themaster cylinder through nipple (10), fluid line (16) directly into theinterior of the brake cylinder (44), as shown in FIG. 6, of the discbrake. Braking action as known for floating caliper disc brakes is nowinitiated and the brake shoes (46) or brake pads are moved by means ofthe brake cylinder (44) being incorporated and movable in axialdirection in the spherical joint (54) or by piston (43) until they havecontact with the brake disc (47).

With reference to FIG. 6, the spherical joint (54) is to fulfill severaltasks. It helps to make the whole system production-friendly related,e.g., to the attachment of the disc brake. The holding device of thebrake cylinder unit, bonded to the fork tube (38,39), as shown in FIG.4, does not have to be precisely parallel to the brake disc before beingsoldered or welded, because of the swivelling and cone-like slidingmotion possible for the ball joint in the divided ball socket (25)allowing parallelism between brake pads respectively the brake disc byadjustment. This divided ball socket (25) will, after adjusted parallelpositioning of brake disc and brake shoe be drawn together by means ofbolts, gripping so the ball joint (54) this latter then being solidlyconnected with the bicycle frame.

Further, therefore, the axial bore in the ball joint (54), as shown inFIG. 6, has at some time to serve as a guiding device for the floatingbrake cylinder (44) and the slot (56) of the ball joint sleeve, the balljoint (54) with the nipple (49) connecting the fluid line with the brakecylinder are utilized to prevent the disc brake cylinder (44) fromrotating.

To fix the brake disc (47) on the hub (35) a thread is cut on one sideof the hub, as known for rear wheel hubs to attach the idling sprockets.It is then necessary to have a shoulder in front of the spoke flange andkeyways or indentations foreseen.

The center of the brake disc (47) is formed so that the disc (47) withkeys worked in or inserted can be drawn over the thread of the hub (35)and the brake disc (47) is secured on the hub (35) by means of a nut(48).

This kind of attachment for the brake disc (47) makes it possible, thatnearly all customary front wheel- and rear wheel hubs can be equippedwith the disc brake (47) by a few more operations done during hubmanufacturing.

What is claimed is:
 1. A bicycle brake for use with a bicycle having awheel with the rim, comprising at least one master cylinder, a handlever connected to said master cylinder, at least one brake cylinderconnected with said master cylinder by a hydraulic fluid line, a brakeshoe connected to said brake cylinder and positioned near said wheel,and a support, wherein said brake cylinder is connected with saidsupport and said support includes means for tilting said brake cylinderaway from said wheel, wherein said brake is adapted to be attached to afork tube of a bicycle via said support, and said brake further includesa support bolt having an axis, wherein said support bolt is attached toand extends from said fork tube, and wherein said support is axiallydisplaceable on said support bolt, said means for tilting comprisingsaid support and said support bolt being formed such that at an axialdisplacement over a certain length by said support on said support bolt,said support can be turned around said axis of said support bolt.
 2. Thebicycle brake according to claim 1, wherein said support includes aspherical joint which receives said brake cylinder.
 3. The bicycle brakeaccording to claim 1, further including a pressure spring positioned onsaid support bolt for providing a force, wherein said support is axiallydisplaceable on said support bolt against said force provided by saidpressure spring so as to allow said support to turn around said axis. 4.The bicycle brake according to claim 1, wherein said support includes abore engaging said support bolt and extending substantially parallel theradial direction of said rim, wherein with said axial displacement onsaid support bolt, said support can be turned around the axis of saidsupport bolt substantially transverse to the radial direction of saidrim.
 5. The bicycle brake according to claim 1, wherein said hydraulicfluid line has at least two ends which are connected with a space ofvariable volume defined in said master cylinder and said brake cylinder,wherein said space in said master cylinder can be reduced by means of ahand lever acting against a force accumulator positioned in a closedhollow body defining said space in said master cylinder, wherein saidhollow body includes a casing made of a substantially leakproof elasticmaterial, said casing connected on one side with a disc piston and onanother side with a guiding flange, further comprising a pushing rodguided by said guiding flange and maintained against the bottom of saidpiston, wherein said pushing rod is not in contact with said elasticmaterial in the axial direction.
 6. The bicycle brake according to claim5, wherein a threaded pin is positioned in a round bolt and wherein saidround bolt is rotatably located in a joint of said hand lever and saidthreaded pin is adapted to push against said pushing rod.
 7. The bicyclebrake according to claim 5, wherein a leakproof connection is providedon one side of said master cylinder adjacent said disc piston and aninlet flange is provided on another side of said master cylinder, saidinlet flange connected to a hydraulic fluid line, wherein in said mastercylinder hydrostatic pressure is transformed to braking force which actsagainst said brake piston for transmitting said force to said brakeshoe.
 8. The bicycle brake according to claim 5, wherein said brakecylinder includes a brake piston movable in said space and whichincludes an annular groove for engaging a gasket ring.
 9. The bicyclebrake according to claim 5, wherein said master cylinder includes ahousing with a front face and a pressure spring acting as a forceaccumulator positioned between said disc piston and said front face. 10.The bicycle brake according to claim 5, wherein said support has anaxially slotted ball joint, and said brake cylinder is positioned insaid axially slotted ball joint and axially movable and slidable,wherein said brake cylinder is clamped within said support via a lockingscrew, said support allowing said brake cylinder to be adjustablypositioned relative to said wheel rim.
 11. The bicycle brake accordingto claim 10, wherein said slotted ball joint is slotted in the axialdirection and held by said support, and wherein said support isU-shaped.
 12. The bicycle brake according to claim 10, wherein said balljoint includes a slotted sleeve and said brake cylinder is preventedfrom rotating via a pin fixed on said brake cylinder and guided in aslot of said slotted sleeve.
 13. The bicycle brake according to claim12, wherein said ball joint and said sleeve are adjustable and slidable,having movement in two planes and wherein said ball joint can be lockedwithout impairing floating movement of said brake cylinder.
 14. Thebicycle brake according to claim 5, further comprising a disc adapted toattach to said wheel and means associated with said master cylinder forengaging said disc for forming a disc brake.
 15. The bicycle brakeaccording to claim 14, wherein said disc is fixed to a hub of said wheelof a bicycle by means of keys and prevented for falling off via a lockednut.
 16. The bicycle brake according to claim 1, wherein said rim has aradial direction extending through said rim and an axial directionsubstantially transverse to said radial direction, wherein said supportincludes a bore and is connected to said bicycle via said support boltextending from said bicycle and through said bore, wherein said boreextends substantially parallel said radial direction of said rim andwherein said means for tilting said brake cylinder further comprisessaid support being tiltable through an angle α on said support bolt,wherein said angle α is substantially transverse to said radialdirection.
 17. A bicycle brake for use with a bicycle having a wheel anda fork tube, comprising:at least one master cylinder; a hand leverconnected to said at least one master cylinder; a support bolt having anaxis and attached to and extending from said fork tube; a supportincluding means for being tilted by an angle (α) away from said wheeland which is displaceable on said support bolt, wherein said means forbeing tilted comprises said support and said bolt being formed such thatover an axial displacement of said support on said bolt of a certainlength, said support can be turned around said axis of saidmulti-cornered bolt; at least one brake cylinder connected with at leastone master cylinder by a hydraulic fluid line and comprising a brakeshoe positioned near said wheel and connected with said brake cylinder,wherein the brake cylinder is connected with said support and istiltable with said support, said brake cylinder including a brake pistonwhich has a front surface which holds said brake shoe on said brakecylinder, wherein said brake piston is formed such that in partialregions of said front surface, an inward bent base of said brake shoecan snap into a circular groove of said front surface such that a hooklike grip is exerted onto said front surface of said piston, whereinsaid front surface of said piston is in close contact with said base ofsaid brake shoe for transferring braking forces, and wherein said pistonincludes a head having a cylindrical portion which is adapted to receiveradial forces.